Releases for Spectra Background Remover - Subtract common spectroscopic background functions

• Added double exponential function.
• Rearranged controls for clarity.

• Re-positioned some controls for consistency.
• Follow Data checkbox has been added to the exponential and polynomial functions.
• Minor bug-fixes and code improvements.

• Fixed error on bad input to BackgroundSubtractGUI().
• Previous settings are now loaded from saved background waves (ending "_bck").
• Added setting for Tougaard band-gap (T₀) smoothing and a link setting between parameters D and C.
• Generated scattering CS data from the parametric Tougaard type will be exported as well (ending "_scs").
• Output waves are now saved in the same folder as the input.
• Smoothing of the step function can now be set in a wider range.
• Now multiple instances of the tool can be opened at the same time.
• Parameters will be written into background waves when calling GenerateBackground() in user code as well.
• Rearranged control layout and added 'Plot after Export' function to create a graph of exported background data.
• Added support for keyboard-shortcut (and other future) settings via external text file.

• The polynomial coefficients are now displayed in the legend and saved in the output.
• Fixed several bugs with the polynomial background when called from user code without the GUI:
  • error because folder was not present.
  • error when selected range is close to the full data range.
  • error when polynomial degree is invalid.

• Minor code refactoring.
• Now background function settings are saved into the output's notes.
• If multiple backgrounds are subtracted then each setting is recorded successively.

Minor window and control size adjustments for an improved layout on Mac.

Made sure the Data Browser is open upon calling and made some minor control size adjustments.

Initial public release of this project.